Conventionally, a disk array controller is known to copy data stored in a storage apparatus that is predicted to malfunction among a plurality of storage apparatuses. The disk array controller copies the data in its surplus storage space that is created due to the plurality of storage apparatuses having different storage capacities. In a case where the storage apparatus predicted to malfunction actually malfunctions, a CPU (Central Processing Unit) of the disk array controller allows access for reading or writing data with respect to the surplus storage including the copied data when the malfunctioned storage apparatus is accessed for reading or writing data thereto.
Patent Document 1: Japanese Laid-open Patent Publication No. 2010-160623
However, the conventional disk array controller does not taking into consideration a case where the prediction of a malfunction is wrong. Therefore, a wrong prediction leads to a waste of resources in a case where the disk array controller has already copied data from a storage apparatus predicted to malfunction.